Masaaki Sato

Trumpet sound simulation using a two‐dimensional lip vibration model

Trumpet sound simulation is carried out with a two‐dimensional lip vibration model, where the lips execute both swinging and stretching motions. This model allows lips to operate on both the lower and higher frequency sides of the air‐column resonance frequencies. Oscillations generated by the total sound production system are on both the lower and higher frequency sides in the first through third resonance modes, while in the fourth and higher modes they are realized only on the lower side. From each resonance mode, an oscillation having the least frequency deviation against a change in lip eigenfrequency and also having sufficient amplitude is selected as the optimum oscillation of the resonance mode. It is found that these oscillations in the lower modes have positive phase differences between lip vibration and mouthpiece pressure, whereas those in the higher modes have negative ones. This result closely matches the transition of lip vibration states from the one modeled by the outward‐striking valve a...

Signal processing circuit for binaural signals

A binaural signal processing circuit comprising a first system for imparting an input signal with a transfer characteristic equal to the transfer characteristic hL(t; θ, r) from a sound source to the left ear of a listener, where θ represents an angle between the front direction of the listener and the sound source, and r represents a distance between the sound source and the listener, a second system for imparting the input signal with a transfer characteristic equal to the transfer characteristic hR(t; θ, r) from the sound source to the right ear of the listener, a system for variably controlling the transfer functions of the first and second transfer function imparting systems, and a further system for deriving binaural signals from the first and second transfer function imparting systems.

Time‐domain simulation of sound production in the brass instrument

Sound production in brass instruments is formulated physically with two different models of lip vibration: the ‘‘transverse’’ model, where lips strike laterally to the direction of the air flow, and the ‘‘swinging‐door’’ model, where lips execute an outwardly striking motion. This formulation is used to carry out time‐domain simulation, which indicates that self‐excitation of the brass instrument is possible with both of these lip models. Changing the lip resonance frequency provides sustained oscillation at the first through eighth air column resonance modes, which correspond to the musical tones in the harmonic series played on the brass instrument without valve manipulation. Oscillation probably also occurred at higher modes, but that region was not investigated. The harmonic structure of the simulated sound varies according to the fundamental frequency and sound level, as is the case in the sound produced by actual brass instruments. Unusual regimes of oscillation are also obtained: the pedal tone, wh...

Miniature stereo device with extensible speakers

A miniature stereo device which provides a satisfactory stereo effect includes a main body having an audio device which generates a stereo output, and a pair of speakers positioned at both sides of the main body for reproducing the stereo output. One of the speakers is arranged to be extended to a position at which it is separated and fixed relative to the other speaker at a desired distance, in order to obtain an optimum stereo effect.

Ultra-small portable sound reproducing apparatus

A loudspeaker holder including a baffle plate and a loudspeaker supported by the baffle plate is rotatably coupled to a portable sound reproducing device having an operating surface and an audio-amplifier for supplying a power output signal to the loudspeaker through a pin and opening coupling means. To utilize the loudspeaker, the loudspeaker holder is rotated about the pin to form a space between the baffle plate and the operating surface. The sounds generated by the loudspeaker are transmitted to the outside through the space and an opening provided in the baffle plate. In case of carrying the portable sound reproducing device, loudspeaker holder is rotated about the pin to bring the baffle plate into contact with the operating surface, and to extinguish the space.

Brass sound simulation with a lip vibration model having two degrees of freedom

Brass sound simulation is carried out with the use of a two‐dimensional lip vibration model, where lips execute both rolling and reciprocating motions. This model allows lips to operate on both the lower and higher frequency sides of the air‐column resonance frequencies. Oscillations generated by the total sound production system are on both the lower and higher frequency sides in the first and second resonance modes, while in the higher modes they are realized only on the lower side. The harmonic series selected from these oscillations in the second and higher modes to achieve the optimum pitch turns out to comprise an oscillation on the higher side of the second resonance frequency and oscillations on the lower sides of the higher resonance frequencies. This result closely matches the transition of lip vibration states from the outward‐striking vibration at the second mode (i.e., the lowest mode among the ones used musically) to the vocal‐cord‐like vibration at the higher modes, which is observed in the...